The present invention is directed to bicycles and, more particularly, to an adapter assembly for a bicycle bottom bracket.
A bicycle bottom bracket is a cylindrical tube portion of the bicycle frame used to rotatably mount the pedal assembly to the bicycle. The pedal assembly usually comprises right and left crank arms, each of which has a pedal attached to one end. The other end of each crank arm is attached to an axle that extends through the bottom bracket. A bearing assembly is disposed between the axle and the bottom bracket at each side of the bottom bracket for rotatably supporting the axle, and one or more front sprockets usually are attached to the right side crank arm for driving the bicycle chain.
The front sprocket(s) must be properly aligned with the rear sprocket(s) attached to the rear wheel so that the bicycle operates properly. Thus, the axle must be properly positioned laterally within the bottom bracket. To accomplish this, adapter members screw into the bottom bracket, and the axial positions of the adapter members are adjusted using spacers inserted between the adapter members and the side edges of the bottom bracket. If the bearing assemblies are mounted to the adapter members, then preferably some sealing mechanism is provided for preventing contaminants such as dust or water from entering the bearing assemblies. Known seals are only partially effective for that purpose.